Electrical ignition apparatus



Oct. 20, 1942. F, MlESS 2,299,642

ELECTRI CAL IGNITION APPARATUS Filed Aug. 30, 1940 F950 M555 @f 1 Patented Oct. 20,l 1942 UNITED STATES PATENT OFFICE 2,299,642 ELECTRICAL IGNITION APPARATUS Fred Miess, Gary, Ind. Application August 30, 1940, Serial No. 354,887

Claims.

This invention relates to electrical ignition apparatus, and more particularly to those which are used in connection with the fuel nozzles of an industrial furnace, although not limited thereto. Such apparatus supply strong electrical impulses of short duration.

One of the objects of the 'present invention is that it provides very effective ignition with a very low electrical power consumption.

Another object is to provide a simple, rugged, reliable and sparkless means of rapidly and alternately closing and opening a charging circuit and a discharging circuit.

The foregoing and other objects will be apparent from the following specification and the drawing, in which:

Figure 1 is a diagram illustrating in section certain details of construction; and

Figure 2 is a sectional view on the line 1li-l1 of Figure 1.

As pointed out in my co-pending application, Serial No. 245,765, filed December 14, 1938, ignition apparatus now in general use is of two main types. One is the make-and-break type found in automobile or other internal combustion engine ignition systems, where a primary circuit of a-stepup transformer is opened and closed to effect periodic generation of energy in the secondary of the transformer. The other is the type more generally found in industrial applications, and consists of a step-up transformer directly connected to an alternating current line, so that there is a continuous arcing across the ignition points. This latter type makes a very simple, rugged and reliable ignition system especially adapted to the supplying simultaneously of ignition impulses to a large number of gaps or pairs of points. This type, for example, is generally found on industrial furnaces having large numbers of fuel jets or burners as, for example, annealing furnaces in the steel industry. For reasons concerned with safety, such ignition apparatus is generally run continuously while fluid fuel is being supplied to the furnace; and

this results in one of the principal objectionable features of such a system, a large energy consumption. v

The present invention is fundamentally similar to that of my co-pending application, Serial No. 245,765, but provides a more rugged and simple apparatus with greater capacity.

Referring more particularly to the drawing, the numeral I0 designates a motor which is suitably connected to a shaft II, the latter in turn being journaled in a pair of spaced aligned bearings I2 whereby it is suitably mounted for rotation at a given desired speed. Disposed intermediate the bearings I2, the shaft I I carries a pair of spaced collector rings I4 and I5. Disposed between the collector rings I4 and I5, the shaft Il carries a hub to which there is suitably connected a disk 22 of electrical insulating material and which carries on its periphery a pair of opposed electrical contact segments 23 and 24. The disk 22 is composed of any suitable electrical insulating material whereby the contact segments 23 and 24 are maintained electrically insulated from said shaft and also from each other.

The collector ring I4 on the shaft II is electrically connected to the contact segment 23 by means of a wire 26, while the collector ring I5 is connected to the contact segment 24 by a wire Disposed beneath the shaft II and in a position facing the contact segments 23 and 24 is a mercury well which is provided with a spout 3l so constructed yand arranged as to project mercury onto the said contact segments when they occupy the lowermost position in their periods of rotation with the shaft II. Mercury is supplied to the mercury well 30 through a feed line 33 which is connected with a suitable mercury pump 35, the latter preferably being of that type which is described and claimed in my copending application, entitled Centrifugal pump, filed August 27, 1940, and bearing Serial No. 354,432. g v

Disposed immediately below the disk 22 which carries the contact segments 23 and 24 there is provided a well 3l which receives the mercury after it has been projected onto the said segments. From the well 3'I the mercury passes through an aperture 38, tube 39, and back into the mercury circulating system which comprises the mercury pump 35.

The stream of mercury, designated at X, is projected onto the segments 23 and 24 as they occupy their lowermost positions and will be cut thereby for the purposes of breaking a circuit and accomplishing results which will appear more fully hereinafter.

In Figure 1, the numerals and 4I designate power lines connected to a suitable source of direct current. The line 40 is connected through a double pole single throw switch 43 to a line 45 which is connected in series to an electrical check-valve 41 (i. e., Tungar bulb or the like), inductance 48, resistance 4., and then to a collector ring brush which makes contact with the collector ring I4. Referring to thel lower 56 and 61.

left-hand portion of Figure 1. the line 4| is connected through the double pole single throw switch 43 with a line 55 which connects with the former of a pair of power lines 56 and 51 through the medium of a double `pole single throw switch 58. The line 51 is connected through the double pole single throw switch .58 with a line 60. The line 60 is connected to a collector ring brush 6| which makes contact with the collector ring I5. .Across the lines 60 and 55 (which are the output wires) there is disposed a permanently connected load 63 which is just ahead of the switch 58 (which vis the output switch). With a very light load the contact between the segment 24 and the mercury stream.

might separate before condenser 66 were completely discharged, that is, while current still owed in the discharge circuit. Under this condition, sparking would occur at the point of separation of the contact. The permanently connected load 63 is so constructed and arranged as to discharge the condenser 66 in the allotted time even with no load connected to the lines Through the output switch 58 impulses are fed to a two-wire distribution circuit comprising the lines 56 and 51.

Between 'the switch 43 and the permanently connected load 63 the line 55 is connected with the mercury well 30 by means of a line 65 in which there is disposed an electrical condenser 66 of considerable capacitance.

In operation:

With the shaft il in the position sho-wn in Figure 1, one side of the condenser 66 is connected through the lines 65 and 55 and the switch 43 to the line 4| of the direct current source. 'Ihe other side of the condenser 66 is connected through the line 65, mercury stream X, segment 23, wire 26, collector'ring Hl, collector ring brush 56, resistance 49, inductance 48, electrical "check-valve 41, line 45 and switch 43 to the line 40 of the direct current source. Thus the condenser 66 receives a charge during the time that the segment 23 is in contact withy the mercury stream X. A little later, in the revolution of the shaft Il, this contact is broken and the charging circuit is opened.

A little later in the revolution of the shaft Il, the segment 24 makes contact with the mercury stream X, establishing a circuit from the condenser 66 through the line 65, mercury stream X, segment 24, wire 21, collector ring I5, collector ring brush 6|, line 66 and switch 58 to the line 51 of the discharge circuit. The other side of the condenser 66 is already connected through the line 65, line 55 and switch 58 to the line 56 of the discharge circuit. Thus the condenser 66 discharges its stored energy into the lines 56 and 51 and partly or wholly into the permanently connected load 63, depending on the amount of load connected to the said lines.

Still a little later, in the revolution of the shaft Il, contact between the segment 24 and the mercury stream X is broken, thus opening the discharge circuit, after which the charging circuit is again closed and the cycle repeated indenitely.

By properly proportioning the resistance 49 of the tunedf charging circuit, it may be given any desired decrement and thus permit of the charging of the condenser 66 to a voltage which is either equal to or higher or lower than the voltageof thechargingr source. This eliminates the necessity of a motor generator or other source of special voltage as a charging source; and will permit the use of a standard 250 volt direct current house circuit as a charging source.` 'I'he tuning can be done very accurately in the case of a direct current circuit of steady Voltage, and steady speed of the switching means. A fluctuating voltage or speed of the switching means might introduce some discrepancies; and in order to eliminate this possibility, there has been included in the charging circuit the electrical check-valve 41 in the form of the Tungar bulb. This electrical check-valve is not used as an ordinary rectifier to supply direct current from an alternating current source, but is used in connection with the "tuned charging circuit to hold the current at Zero value until the charging circuit has been opened by the switching means. In other words, the "tuned circuit brings the charging current to zero value at the desired time; and the check-valve holds the current at zero value until the charging circuit is opened. This period might extend over any number of oscillation cycles and the current still remain continuously at zero value. This,

obviously, is not true of ordinary rectification where the current would be. at zero value only during every other half cycle.

While I have shown and described one specic embodiment of the present invention, it will be seen that I do not wish to be limited exactly thereto, since various modifications may be made without departing from the scope of the invention, as defined by the following claims.

I claim:

1. Apparatus of the character described for periodically supplying a strong electrical impulse of short vduration from a source of electrical energy, including: a condenser; a source of current adapted to charge said condenser; an inductance in the charging circuit of said condenser, said inductance being so proportioned with respect to the capacitance of said condenser as to provide a tuned charging circuit; and means for periodically disconnecting said condenser from said source and connecting it to the circuit to which said strong impulse is to be the capacitance of The provision of the inductance 48 and the resistance 49 accomplishes two highly desirable results. By the proper proportion of the inductance 48 to the capacitance of the condenser 66, the charging circuit may be "tuned to bring the charging current to -zero value at the lnstant that the charging circuit is to be opened, thus securing sparkless operation of the circuit.

delivered.

2. Apparatus of the character described for periodically supplying a strong electrical impulse of short duration from a source of electrical energy, including: a condenser; a source of current adapted to charge said condenser; an inductance in the charging circuit of said condenser, said inductance being so proportioned with respect to said condenser as to provide a tuned charging circuit; a resistance in the charging circuit of said condenser, said resistance being proportioned with respect to said inductance and the'capacitance of said condenser to give the desired decrement to condenser voltage oscillation; and means for periodically disconnecting said condenser from said source and connecting it to the circuit to which said strong impulse is to be delivered.

3. Apparatus of the character described for periodically supplying a strong electrical impulse of short duration from a source of electrical energy, including: a condenser; a source of current adapted to charge said condenser; an inductance in the charging circuit of said condenser, said inductance being so proportioned with respect to the capacitance of said condenser as to provide a tuned charging circuit; an electrical check valve in the charging circuit of said condenser; and means for periodically disconnecting said condenser from said source and connecting it to the circuit to which said strong impulse is to be delivered.

4. Apparatus of the character described for periodically supplying a strong electrical impulse of short duration from a source of electrical energy, including: a condenser; a source of current adapted lto charge said condenser; an inductance in the charging circuit of said condenser, said inductance being so proportioned with respect to the capacitance of said condenser as to provide a tuned charging circuit; a resistance in the charging circuit of said condenser, said resistance being proportioned with respect to said inductance and the capacitance yof said condenser to give the desired decrement to condenser voltage oscillation; an electrical check valve in the charging circuit of said condenser; and means for periodically disconnecting said condenser from said source and connecting it to the circuit to which said strong impulse is to be delivered.

5. Apparatus of the character described for periodically supplying a strong electrical impulse of short duration from asource of electrical energy, including: a condenser; a source of current adapted to charge said condenser; an inductance in the charging circuit of said condenser, said inductance being so proportioned with respect to the capacitance of said condenser as to provide a tuned charging circuit; a resistance in the charging circuit of said condenser, said resistance being proportioned with respect to said inductance and the capacitance of said condenser to give the desired decrement to` condenser voltage oscillation; an electrical check valve in the charging circuit'of said condenser; a permanently connected load across the discharge circuit of said condenser; and means for periodically disconnecting said condenser from said source and connecting it to the circuit to which said strong impulse is to be delivered.

FRED MIESS. 

